The lift enhancing elements, including trailing edge landing flaps and leading edge slats, provided on the lifting wings of aircraft are conventionally operated or actuated by arrangements including a central drive unit, a respective rotational shaft drive line extending to the left and to the right from the drive unit respectively along the left wing and the right wing, as well as a plurality of decentralized actuator mechanisms. The drive unit exerts a rotational motion and drive power onto the left and right drive lines. From the drive lines, the rotational motion and drive power are applied to the actuator mechanisms, which in turn convert the rotational motion into a translational motion that is applied to the respective connected lift enhancing element, i.e. landing flap or slat. Thereby, the drive unit achieves the desired extension, retraction, or deflection of the respective slats and flaps via the drive lines and the actuator mechanisms. In order to ensure a uniform synchronous actuation of all landing flaps and/or slats, all of the lift enhancing elements of a respective wing are typically mechanically connected to the same single common rotational shaft drive line. Thus, all of the lift enhancing elements connected to the single drive line will necessarily be actuated in unison.
FIG. 1 illustrates an example of an apparatus of the type generally discussed above, for operating or actuating the inboard landing flaps 1 and the outboard landing flaps 2 of the left and right wings of an aircraft (not shown). A central drive unit 7 is centrally located between the two wings, and rotationally drives two synchronized rotational shaft drive lines 5 and 6 that respectively extend into and along the two opposite wings from the central drive unit 7. Each landing flap 1 and 2 is respectively mechanically connected by two actuator mechanisms 3 and 4 to a respective one of the drive lines 5 or 6. The actuator mechanisms 3 and 4 convert the rotational shaft motion of the drive line 5 or 6 into a translational motion that is applied to the connected landing flap 1 or 2, in order to drive the landing flap as required.
It is a serious disadvantage with such a drive arrangement, that mechanical faults or failures of various types, e.g. a jamming of an actuator mechanism or of a lift enhancing element, or a break of a rotational shaft, can potentially lead to a local overloading of the arrangement or to undesirable and improper behavior of the apparatus, for example an asymmetrical actuation of the lift enhancing elements. For this reason, in the event such a fault or failure is recognized, generally the entire apparatus is stopped and arrested in its momentary existing position through the use of braking devices. The disadvantage of such a procedure is that a single mechanical fault or failure of even a single element in the entire apparatus can lead to the complete loss of the entire functionality of the landing flap and slat system.
The above discussed problems or disadvantages are to be overcome at least partially by arrangements that provide a multiplicity of certain individual components as well as a mechanical decoupling of various components of the apparatus. This is to enable a partial further operation of the apparatus even in the case of a localized mechanical failure. An example of such an apparatus is illustrated in FIG. 2, whereby the drive units and the rotational shaft drive lines have been duplicated. In other words, this arrangement includes a first drive unit 7 connected via first rotational shaft drive lines 5A and 6A to the inboard landing flaps 1 via the connected actuator mechanisms 3 and 4, as well as a second drive unit 8 that drives the outboard landing flaps 2 through second rotational shaft drive lines 9 and 10 via the connected actuator mechanisms 3 and 4. This provides two separate drive arrangements, namely one for the inboard flaps and one for the outboard flaps. In the event of a localized fault, such as a jamming or a failure of one drive unit or one actuator mechanism, or a break of a shaft drive line, a partial operability of the unaffected drive arrangement continues, but a substantial loss of the apparatus functionality cannot be avoided.
FIG. 3 schematically illustrates a further apparatus with an even higher degree of separation of sub-systems, comprising plural decentralized drives 11 that are entirely mechanically separate from one another, and that are each respectively individually connected to an associated rotational shaft drive line 12 for respectively driving a single inboard or outboard landing flap 1 or 2 via the connected actuator mechanisms 3 and 4. Even in such an arrangement, in the event of a failure of any one of the apparatus components, a partial loss of the apparatus functionality will still arise, because at least the affected sub-system (and possibly also its symmetrical counterpart) must be shut down. Also, due to the increased number of drives 11, and the like, such an apparatus suffers an increased complexity and increased weight in comparison to simpler systems.